Calculate Value Types (int, float, string) Sizes In C# With Generic Method

Question

I want to write method which calculate value types size. But i can't give value types (int, double, float) as method parameter.

   /*
    *When i call this method with SizeOf<int>() and 
    *then it returns 4 bytes as result.
    */
   public static int SizeOf<T>() where T : struct
   {
       return Marshal.SizeOf(default(T));
   }

   /*
    *When i call this method with TypeOf<int>() and 
    *then it returns System.Int32 as result.
    */
   public static System.Type TypeOf<T>() 
   {
       return typeof(T);
   }

I don't want it that way.I want to write this method as below.

   /*
    *When i call this method with GetSize(int) and 
    *then it returns error like "Invalid expression term 'int'".
    */
   public static int GetSize(System.Type type)
   {
       return Marshal.SizeOf(type);
   }

So how can i pass value types (int, double, float, char ..) to method parameters to calculate it's size as generic.

possible duplicate of how to get byte size of type in generic list? — Avantol13
– Avantol13, Commented May 12, 2015 at 19:45

Amit · Accepted Answer · 2015-05-12 19:51:25Z

1

The reason you get an error for GetSize(int) is that int is not a value. You need to use typeof like so: GetSize(typeof(int)), or if you have an instance then: GetSize(myInt.GetType()).

answered May 12, 2015 at 19:51

Amit

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Comments

usr · Accepted Answer · 2015-05-12 19:49:26Z

1

Your existing code just works:

public static int GetSize(System.Type type)
{
    return Marshal.SizeOf(type);
}

Not sure where that error is coming from that you posted but not from this. If you want to you can make this generic:

public static int GetSize<T>()
{
    return Marshal.SizeOf(typeof(T));
}

answered May 12, 2015 at 19:49

usr

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2 Comments

Alex Over a year ago

It appears the mystery about OPs error message is due to calling GetSize(int) instead of GetSize(typeof(int))

usr Over a year ago

Has he posted the code it would have been obvious. Good guess.

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